/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans;

import java.beans.PropertyDescriptor;

/**
 * The central interface of Spring's low-level JavaBeans infrastructure.
 * 
 * <p>
 * Typically not used directly but rather implicitly via a
 * {@link org.springframework.beans.factory.BeanFactory} or a
 * {@link org.springframework.validation.DataBinder}.
 * 
 * <p>
 * Provides operations to analyze and manipulate standard JavaBeans: the ability
 * to get and set property values (individually or in bulk), get property
 * descriptors, and query the readability/writability of properties.
 * 
 * <p>
 * This interface supports <b>nested properties</b> enabling the setting of
 * properties on subproperties to an unlimited depth. A <code>BeanWrapper</code>
 * instance can be used repeatedly, with its {@link #setWrappedInstance(Object)
 * target object} (the wrapped JavaBean instance) changing as required.
 * 
 * <p>
 * A BeanWrapper's default for the "extractOldValueForEditor" setting is
 * "false", to avoid side effects caused by getter method invocations. Turn this
 * to "true" to expose present property values to custom editors.
 * 
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 13 April 2001
 * @see #setExtractOldValueForEditor
 * @see PropertyAccessor
 * @see PropertyEditorRegistry
 * @see BeanWrapperImpl
 * @see org.springframework.beans.factory.BeanFactory
 * @see org.springframework.validation.BeanPropertyBindingResult
 * @see org.springframework.validation.DataBinder#initBeanPropertyAccess()
 */
public interface BeanWrapper extends ConfigurablePropertyAccessor, TypeConverter {

	/**
	 * Change the wrapped JavaBean object.
	 * 
	 * @param obj
	 *            the bean instance to wrap
	 */
	void setWrappedInstance(Object obj);

	/**
	 * Return the bean instance wrapped by this object, if any.
	 * 
	 * @return the bean instance, or <code>null</code> if none set
	 */
	Object getWrappedInstance();

	/**
	 * Return the type of the wrapped JavaBean object.
	 * 
	 * @return the type of the wrapped bean instance, or <code>null</code> if no
	 *         wrapped object has been set
	 */
	Class getWrappedClass();

	/**
	 * Obtain the PropertyDescriptors for the wrapped object (as determined by
	 * standard JavaBeans introspection).
	 * 
	 * @return the PropertyDescriptors for the wrapped object
	 */
	PropertyDescriptor[] getPropertyDescriptors();

	/**
	 * Obtain the property descriptor for a specific property of the wrapped
	 * object.
	 * 
	 * @param propertyName
	 *            the property to obtain the descriptor for (may be a nested
	 *            path, but no indexed/mapped property)
	 * @return the property descriptor for the specified property
	 * @throws InvalidPropertyException
	 *             if there is no such property
	 */
	PropertyDescriptor getPropertyDescriptor(String propertyName) throws BeansException;

}
